Short peptides containing the sequence ARG-GLY-ASP (RGD) bind to cell adhesion receptor--integrins--promoting cell attachment when insolubilized onto a surface and inhibiting it when added in solution. Those peptides have become important tools in the analysis of cell adhesion and show promise as potential therapeutic agents. The overall objective for the research proposed here is to develop an understanding of the conformational basis for potency and specificity of the RGD peptides for the binding sites of individual integrins. We will examine conformational properties of the currently availalbe linear compound GRGDSP and related cyclic analogues, as well as the conformation of RGD in the naturally occurring adhesive proteins. The results will be related to their specificity of binding the RGD receptors. This approach integrates the use of synthetic peptide chemistry, biological evaluation, crystallography, NMR spectroscopy and theoretical imaging analysis. It is expected that peptides with improved receptor specificities and affinities will be obtained.